1 / 12

Second lecture

Second lecture. Plasma proteins. 2-Globulins : (2.7%) a globulins and b globulins: Transport lipids and fat soluble vitamins. g globulins: Antibodies. . Plasma proteins. 2-Globulins : (2.7%). Synthesis In lymphocytes (T and B)

tan
Download Presentation

Second lecture

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Second lecture

  2. Plasma proteins 2-Globulins: (2.7%) • a globulins and b globulins: • Transport lipids and fat soluble vitamins. • g globulins: • Antibodies.

  3. Plasma proteins 2-Globulins: (2.7%) • Synthesis • In lymphocytes (T and B) • Made in response to presence of antigen (“foreign” macromolecule, virus particle etc.) • Functions • Primary function is antigen binding (immune response) • Secondary function is complement binding (after antigen)

  4. Classes of Immunoglobulins • IgG: Microorganisms identification & engulfment. • IgE: Inhibits parasite invasion; involved in allergic reactions. • IgA: • Passive immunity provided by breast milk. • Agglutinates infectious agents in secretions outside the body. • Present in tears & mucous. • IgM: Microorganisms identification & engulfment.

  5. Plasma proteins 3-Fibrinogen: (0.3%) • Structure • MW 340 000 • Sequence of amino acids is known (3000) • 6 polypeptide chains, 2a (67,000), 2b (56,000), 2g (47,000) • Coagulation

  6. separation of plasma proteins • 1-Size Exclusion Chromatography (SEC) • Porous matrix (sephadex). • 2-Affinity chromatography • molecule attached to a column that specifically binds the protein of interest. • Coenzyme / enzyme • Antigen / Antibody • 3-SDS-PAGE (polyacrylamide gel electrophoresis) • Separates by size. • Proteins are complexed with SDS to give the same charge density.

  7. Zone Electrophoresis of Plasma Proteins + - globulins albumin g b a1 a2 6.0 5.6 5.1 4.7

  8. separation of plasma proteins • 4-Precipitation by salts: -Albumin is separated by full saturation with ammonium sulphate. -Globulins are precipitated by half saturation with ammonium sulphate. • 5-Ultra centrifugation: -Plasma proteins can be separated according to their different rates of sedimentations. -The sedimentation rate depends on weight, shape of the molecule & density of suspending medium.

  9. Functions of Plasma Proteins • Maintenance of: • Colloid osmotic pressure. • pH. • electrolyte balance. • Transport of: ions, fatty acids, steroids, hormones etc. • Albumin (fatty acids), ceruloplasmin (Cu2+), transferrin (Fe), lipoproteins (LDL, HDL).

  10. Functions of Plasma Proteins • Nutritional:source of amino acids for tissues. • Hemostasis:(coagulation proteins). • Prevention of thrombosis:(anticoagulant proteins). • Defense against infection:(antibodies, complement proteins).

  11. Synthesis of plasma proteins • All albumin, all fibrinogen and most of the globulins (50-80%) (alpha & beta) are formed in the liver. • Assembly time on ribosome ~ 1-2 min. • t0.5 in circulation - 19 days. • 14 g lost per day. • 0.4 mg synthesized per hour per g of liver. • The remaining part of globulins (gamma) are formed in the lymphoid tissues.

  12. Catabolism of plasma proteins • Plasma proteins circulate not only inside the vascular system but also across the capillary bed into the interstitial fluid and back into the plasma through lymphatic vessels. • Tissue macrophages take up albumin by pinocytosis. • Albumin is broken down within the lysosomes of tissue macrophages to amino acids.

More Related